The hacking group Anonymous claims to have struck again, finding and publishing the private information of 102 police officers who work for BART, the Bay Area Rapid Transit system in the San Francisco area.

It was the hacking group's latest attempt to derail the transit system after a BART officer shot and killed a homeless man in early July. BART tried to quell subsequent customer protests by shutting down cellular service four underground San Francisco train stations.

"Leaked personal data, emails and passwords for 102 #BART police officers," said a post today on Twitter put up by "@YourAnonNews." The post included a link to a website listing home addresses and personal email accounts with their passwords.

A BART spokesman confirmed to ABC News that the employees' information was authentic. The authority referred inquiries to the BART Police Officers Association, from whose website it said the officers' information came. The union's website was down this afternoon.

BART has been mired in controversy since the July 3 shooting of Charles Blair Hill on a train platform. Officers said Hill came at them with a knife, but protesters said they were outraged after his death. Demonstrators stopped trains, organizing their efforts by smartphone and text messages, and said their First Amendment rights were violated when BART cut off cellular signals.

Anonymous, a shadowy and loosely-organized group, says it has been an organizer of the protests. It claimed to have crashed a BART marketing website, and encouraged people to come to a downtown rally at BART stations late Monday. BART closed the stations in response, though it did not cut off cellphone transponders.

"Many of us are activists with the voice for the voiceless," read a message Anonymous said it posted today on Tumblr.com after the police officers' information was published. "Push the wrong buttons and we will exploit what needs to be released to the public. That doesn't mean we condone publications of personal information of innocent bystanders. That is not what Anonymous believes in or follows. We are here for the people, to share to the world the fallacies' that our governments' [sic] Love to entertain us with."

The closing line of the message: "We are Anonymous. We are Legion. We do not forgive. We do not forget. Expect us!"

BART Cellular Shutdown Sparks Legal Questions

Legal scholars said the transit system's decision to shut off cellular service raises tremendous First Amendment issues that may not be addressed adequately by existing laws -- a question of how cellphone service should be regarded. Is it a means of free speech, like a printing press or a bull horn? Or, in a subway station, is it a convenience provided by BART -- a service it has a right to cut off?

The Federal Communications Commission said it was investigating BART's right to cut off cellular service. The ACLU of Northern California held off on filing suit against BART, but sent an angry letter to the FCC, calling BART the "first known government agency in the United States to block cell service in order to disrupt a political protest."

"I think it's very dangerous territory," said Gene Policinski, executive director of the First Amendment Center at Vanderbilt University. "The right to protest is as American as apple pie."